There are various woodworking methods employed in the construction of buildings with wooden members. One method involves the so called "wing lock method" using various attachment devices to construct wooden frames. An example of said wing lock method is the so called "metal fit method", as shown in FIGS. 14 and 15. An example of a "metal fit" joint is illustrated using a metal plate connector B and a metal fixture (not shown) shaped of semi-circle projection arms (bolts and D-shaped pins can also used) to connect together wooden members.
The "metal fit" joint is used for connecting a horizontal wooden member to a vertical wooden member having a special slot to be discussed below. The metal protrusion arms 63 and 64 are provided with end plates 65 and 66, respectively. The end plates 65 and 66 can be attached, for example, by welding. The metal plate 60 is provided with a hole 62 and a U-shaped slot 61 for connecting the metal plate to the horizontal wooden member using bolts.
The method of forming the joint using the metal plate connector B illustrated in FIGS. 16 through 20.
The holes 81, 82 are drilled into the vertical member or column 80. The metal protrusions arms 63 and 64 having welded metal end plates 65 and 66 of the metal plate connector B are inserted into the previously drilled holes 81 and 82 in the column 80, as shown in FIG. 16.
Once the metal end plates 65 and 66 are fully fitted into the drilled holes 81 and 82, the metal plate connector B is hit downwardly with and appropriate tool to set the metal plate connector B firmly in the column 80, as shown in FIG. 17.
As shown in FIG. 18, a pin 93 having a D-shaped pin cross section is inserted into the previously drilled hole 91 in the beam 90. The beam 90 also has a slit provided at its end (not shown). The beam 90 is then moved in the direction of the arrow all the way so that the end grain of the beam 90 meets the column 80 completely.
The beam 90 is then pushed down from its upper side until the pin 93 registers with the bottom of U-shaped slot 61, as shown in FIG. 19. The beam 90 is further forced downwardly with appropriate pressure, and the pin 94 is inserted through the hole 92 in the beam 90, and through hole 62 of the plate B. Nuts are threaded onto and tightened onto the pins 93 and 94, as shown in FIG. 20.
In order to use the metal plate connector B, it is necessary to provide the holes 81 and 82 in the column 80. The holes 81 and 82 are made by such cutting tools as drill bits and rotary bits, however, it is quite possible that the size of the holes may not be accurate depending on the method of drilling such holes. Especially in the situation where the size of the holes are somewhat larger than the size of the metal end plates 65 and 66 of the metal plate connector B, when the metal protrusions arms are inserted into the holes and forced downwardly the joints may not become stable due to space between the holes and the metal end plates 65 and 66. Thus, the metal plate connector B is no longer securely fastened to the column 80, and can easily become loose.
Furthermore, with the metal plate connecters B as explained above, the metal protrusions arms are inserted into the holes and then forced downwardly with an appropriate tool. Thus, the method takes a significant amount of time, and is troublesome due to the requirement of forming holes with the exact size and steps associated with placing the metal connector B into the column 80.